The present invention relates in general to the field of digital subscriber line (xDSL) communications and, more particularly, to a system and method for proxy signaling in a digital subscriber line access multiplexer (DSLAM).
The Public Switched Telephone Network (PSTN) was originally designed for carrying analog voice communication signals. However, users are increasingly using the PSTN to transmit digital data. A typical PSTN network includes numerous central offices. Communication between the central offices can be accomplished through high speed switched digital links. Local loops couple the central offices to the customer premises. The local loops can be analog networks of twisted pair copper wiring. These analog local loops are often referred to as the Plain Old Telephone System (POTS).
The central office typically includes, among other elements, a bandpass filter that can limit the bandwidth of the local loop to approximately 3.3 kHz (between 300 Hz and 3.4 kHz). This is done so that numerous voice-grade local loop lines can be digitized and multiplexed together for transmission between central offices over the switched digital links.
Current computing environments necessitate the need for digital transmission of data. Several services such as leased or switched lines enable such data traffic, but can be prohibitively expensive. Similarly, replacing the telephone infrastructure with a medium that is more conducive to digital traffic can also be prohibitively expensive. Therefore, users desire to use POTS lines to transmit digital data.
Conventional modem technology is one such method of transmitting digital data over POTS lines. This technology attempts to transmit high speed data over POTS lines within the limits of the allocated voice bandwidth, or below 3.4 kHz.
Digital Subscriber Line (xDSL) technology, on the other hand, can apportion the transmission of data over POTS lines into a voice channel and a digital channel. The voice channel can include signals below 4 kHz while the digital channel can include signals above 4 kHz. As such, xDSL can provide a method to increase the bandwidth of the existing telephone network infrastructure.
Furthermore, xDSL technology can allow conventional electronic devices that use the voice channel, and xDSL devices such as transceivers, to couple to the same POTS network. Furthermore, the conventional devices and the xDSL devices can communicate simultaneously over the same wiring, using the respective channels. To accomplish this task, splitters or filters can be used to separate the two channels. Typically, a splitter or filter is placed both at the central office and the customer premises of an xDSL network.
In order to further enable xDSL communication, a central office typically includes a digital subscriber line access multiplexer (DSLAM). The DSLAM includes a modem pool with a plurality of xDSL transceivers (modems). The xDSL modems of the DSLAM communicate with the xDSL modems at the customer premesis over the digital channel.
In order to transmit the xDSL communication from the DSLAM to the public network, a virtual connection (VC) must be established. Conventionally, such connections are established as permanent virtual connections (PVCs) established between the customer premises equipment (CPE) and the public network. Such PVCs are commonly understood in the art, and explained by such specifications as user network interface (UNI) protocol, and network to network interface (NNI) protocols. Typically, several PVCs are established for each modem in the modem pool.
PVCs are disadvantageous, however, because a conventional system employing PVCs must establish PVCs for each modem in the modem pool of the DSLAM whether or not the PVC is currently in use. Opening PVCs to the public network incurs a cost, then, whether or not the PVC is in use.
Switched virtual connections (SVC) are connections established under a conventional protocol. An SVC is established only when necessary for communication between CPE and the public network. An SVC is a xe2x80x9cnegotiatedxe2x80x9d connection, meaning the two endpoints of an SVC communicate and negotiate various parameters of the connection. The endpoints of an SVC connection have xe2x80x9csignallingxe2x80x9d capability if the endpoints are capable of performing this negotiation.
Therefore, for an SVC to be established for DSL communication, the public network and the CPEs in an xDSL network must perform signalling. However, adding such signalling capability into CPE can be expensive, and can drive up the cost of CPE. Additionally, it can be a technical disadvantage that signalling CPE and non-signalling CPE cannot communicate within the same network.
In accordance with teachings of the present disclosure, a system and method for proxy signaling in a digital subscriber line access multiplexer (DSLAM) are disclosed that provide significant advantages over prior developed DSLAMs.
According to one aspect of the present invention, a method for proxy signalling in a DSLAM comprises receiving an indication from a customer premesis equipment that the customer premesis equipment requires a switched virtual connection to a public network. The method further includes recognizing that the customer premesis equipment does not have signalling capability. The method further includes negotiating through a proxy signalling agent located on the DSLAM with the public network on behalf of the customer premesis equipment. A switched virtual connection is established between the proxy signalling agent and the public network. A cross connect is established between the DSLAM and the customer premesis equipment such that the customer premesis equipment can communicate with the public network through the switched virtual connection.
According to another aspect of the present invention, a system for proxy signaling in a DSLAM comprises a CPE list of customer premesis equipment interfaces that require a signalling proxy. The CPE list is maintained according to UNI (ATM) addresses of the customer premesis equipment interfaces. The system further comprises a proxy service agent communicatively coupled to the CPE list. The proxy service agent is operable to recognize a customer premesis equipment interface that requires a switched virtual connection to communicate with a public network. The proxy service agent is further operable to negotiate a switched virtual connection on behalf of the customer premesis equipment interface.
It is a technical advantage of the present invention that switched virtual connections are possible for xDSL communication between customer premesis equipment and a public network. Additionally, such SVCs are possible without the need for adding signalling capability to the customer premesis equipment.
It is an additional technical advantage that the present invention allows non-signalling CPEs and signalling CPEs to co-exist on the same xDSL network. This allows for greater flexibility in the type of services offered to customers of an xDSL provider.
It is a further technical advantage that xDSL service is more economically provided because of the reduction of permanent virtual connections.